Airborne gamma survey of the Sleisbeck mine area

Department of the Environment and Heritage, 2003

Internal Report 400
Pfitzner K, Ryan B & Martin P 2003
Supervising Scientist Division

About the report

Small uranium mines, a mill, and prospects operated in the upper South Alligator River valley from 1956 to 1964 when contemporary environmental rehabilitation legislation did not exist. When mining ceased, the sites were abandoned with no attempt at rehabilitation for minimisation of environmental impacts. A number of field investigations and a hazard reduction program have occurred since mining ceased. In August 2000, Project 1125 ‘Airborne gamma survey of the upper South Alligator River valley’ commenced in order to provide remotely sensed data and images giving information on the state of abandoned uranium mine sites in the upper South Alligator Valley. The project was designed to provide remotely sensed data, including interpretation, to help Parks North in their planning process for rehabilitation of the abandoned uranium mines in the valley, as well as rehabilitation of tailings in the vicinity of Rockhole Mine Creek. Results of this project are outlined in a number of reports (Pfitzner & Martin 2000, Pfitzner et al 2001a, Pfitzner et al 2001b, and, Bollhöfer et al 2001, Pfitzner & Martin 2002).

The airborne gamma survey of the upper South Alligator River valley area highlighted the higher regions of eU and was found to be a time and cost effective method for providing an overview of radiological anomalies due to historical mining activities in the area, and, in determining the location for ground-based studies. As a result of the upper South Alligator River valley study, another airborne gamma survey was commissioned over the abandoned Sleisbeck mine in 2002. Parks North and eriss jointly funded the acquisition of both the upper South Alligator River valley and Sleisbeck airborne gamma datasets.

This report outlines the preliminary results of the Sleisbeck survey. A brief overview of the airborne gamma survey, including a description of the aircraft and survey equipment, follows. A full description of the survey equipment, raw data formats, and the processing steps undertaken by UTS Geophysics prior to receiving the data, are described in the appendix. Examples of the imagery obtained, particularly for the eU channel of the radiometric data, are illustrated. Finally, because field based validations and further interpretations have not yet been performed, the issue of ancillary information and an appropriate disclaimer to be embedded on images passed on to parties other than eriss are discussed.

Future reports may further detail the radiometric, magnetic and elevation data, and possibly other remotely sensed data sets should they become available, as well as field validations should they be required.